Magnetic valve

ABSTRACT

A magnetic valve in which the valve housing with the casing for the valve spool is made of a magnetically uniform piece while the armature of the magnet and the valve spool are likewise made of a magnetically uniform piece, the magnetic flux being passed from the iron casing into the armature of the magnet through the guiding surfaces between the valve housing and the valve spool. By sufficiently dimensioning the diameter of the valve spool and by sufficiently dimensioning the length of the valve spool and thereby the contacting surface thereof, it is possible to maintain the magnetic flux small so that a magnetic jamming of the valve spool with the harmful consequences thereof cannot occur.

United States Patent Dick [45] May 30, 1972 MAGNETIC VALVE 2,853,659 9/1958 Herion ..251/141 x 3,245,652 4/1966 Roth ..25 l/l4l X [72] mimic Dick Gama 3,166,692 l/l965 Forrester et al. ..335/251 [73] Assignee: Voith Getriebe KG, Heidenheim (Brenz),

Germany Primary Examiner-Arnold Rosenthal Attorney-Walter Becker [22] F1led: Feb. 12, 1970 211 App]. No.2 10,761 [571 ABSTRACT A magnetic valve in which the valve housing with the casing for the valve spool is made of a magnetically uniform piece [30] Foreign Application Priority Dam while the armature of the magnet and the valve spool are Feb. 21, 1969 Germany ..P 19 08 659.0 likewise made of a magnetically unifonn piece, the magnetic flux being passed from the iron easing into the armature of the 521 US. Cl. ..l37/625.48, 251/141 magnet through the guiding Surfaces between the valve hous- 511 1m. (:1. ..Fl6k 31/06 s and the valve Spool y sufficiently dimensioning the 581 Field of Search ..251/129,141; l37/625.48, 625.65 diameter of the valve Spool and by Sufiiciently dimensioning the length of the valve spool and thereby the contacting sur- 56] References Cited face thereof, it is possible to maintain the magnetic flux small so that a magnetic jamming of the valve spool with the harmful UNITED STATES PATENTS consequences thereof cannot occur.

2,765,378 10/1956 Perry et al ..l37/625.65 X 5 Claims, 1 Drawing Figure 25- /3 2 H I --h k 20 1 \4 a K 'E 2-- 7 15 MAGNETIC VALVE The present invention relates to a magnetic valve with a coil arranged within an iron mantle or casing for producing a magnetic flux in said casing, and with a magnetic core which is axially movable in the interior of the coil and is adapted by said magnetic flux to be displaced from a rest position into a working position. More specifically, the present invention concerns a magnetic valve of the type mentioned above which is provided with a valve housing associated with said iron casing and provided with a bore extending in'the direction of the magnetic corefor the valve spool and is furthermore provided with a valve spool movably arranged in said bore and associated with the magnetic core.

With heretofore known magnetic valves of the above mentioned type, structural provisions deliberately aim at prevent ing the magnetic flux produced by the coil in the iron casing or at least a material proportion thereof from passing through the fitting gap between the valve bore and valve spool into the magnetic core. This sharp local separation of the magnetic flux from the valve spool entails structural complications which generally have been put up with as unavoidable. There prevails the opinion that when a considerable magnetic flux is passing through the fitting gap, the valve spool will on one hand by said magnetic flux be pressed against the bore for the valve spool by such a strong force that, if it is not immediately blocked, nevertheless the contacting parts will be pressed into a firm metallic engagement and will seize.

In an effort to avoid such damages, while selecting a suitable material magnetizable and non-magnetizable or while selecting the dimensioning of the cross-section accordingly, high magnetic resistances have been built into the path: iron casing fitting gap valve spool magnetic core. Such an arrangement calls for complicated parts not only with regard to their structural shape but also with regard to their manufacture, and makes the assembly, stock keeping and servicing expensive.

, Applicant has found that the heretofore prevailing opinion which lead to the above mentioned steps of complicating magnetic valves is an unjustified prejudice in the art. Actually, as has been found by applicant, no impediment or damage is encountered when the magnetic flux passes through the fitting gap between the valve spool and the bore before entering the magnetic core.

In. view of this finding, it is, therefore, an object of the present invention to considerably simplify the design of magnetic valves. 1

This object and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing which diagrammatically illustrates a longitudinal section through a magnetic valve according to the present invention which is adapted to be flanged to a transmission housing and which is provided with two pairs of control edges on two valve spool webs.

The magnetic valve according to the present invention is characterized primarily in that the valve housing consists together with the iron casing of a magnetically homogeneous piece while the magnetic core with the valve spool consists of a single piece of magnetic material. The magnetic valve according to the invention is furthermore characterized in that the iron casing and the valve housing with the bore for the valve spool on one hand and the magnetic core and valve spool on the other hand are designed in such a manner that, when the magnetic core is attracted into its working position, the magnetic flux is guided from the iron casing and the valve housing into the valve spool and the magnetic core while passing through the cylindrical gap between the bore for the valve spool and the valve spool.

In view of the fact that a flowing of the magnetic flux through the fitting gap cannot only be admitted but is even intended, the magnetic valve becomes particularly simple. The iron casing and the valve housing on one hand and the valve spool and magnetic core on the other hand may be designed as one piece whereby a considerable simplification will be obtained with regard to the construction and manufacture of such pieces, and furthermore a considerable saving in costs will be realized with regard to the assembly, stock keeping and servicing of such valves.

In order to assure that when larger fitting gaps are involved and a relatively great non-uniformity in the fitting gap exists (eccentric position of the valve spool in its bore), the differences in the magnetic flux with regard to the circumference of the valve spool bore will not become too great, it is furthermore suggested that the contacting surfaces between the valve spool and the valve spool bore in the most unfavorable position be dimensioned at least so great that with the magnetic flux necessary for attracting the core, the induction conveyed between the bore and the valve spool web through the gap will not exceed approximately 1,000 Gauss. In order furthermore to assure that with magnetic valves having a valve spool and a valve housing with a plurality of, for instance two, pairs of control edges and with a valve spool in which the control edges are provided at different valve spool webs interconnected by a plunger or the like, the magnetic flux will be distributed uniformly as fast as possible over all valve spool webs, and in order to prevent a concentration of the magnetic flux on that valve spool web which is axially closest to the magnetic core, it is suggested that the plunger have a diameter which is as large as possible.

Referring now to the drawing in detail, the magnetic valve illustrated therein comprises a valve cylinder means generally including a housing 1 of magnetizable material, for instance of cast iron in a single and magnetically uniform piece, with castin control edges 5 and 6 and with openings 4, 7 and 8 for the liquid flows to be controlled. The magnetic valve according to the invention furthermore comprises a one-piece combined magnetic core-valve spool 2 with the magnetic core section 3 and the valve spool section 9. The magnetic valve according to the invention furthermore comprises a magnetic coil 12 which is inserted into a bore 11 which latter is coaxial with the valve spool bore 10. The iron casingfor the coil 12 is at the inlet end of bore 11 closed by a pole cover 13. The magnetic core-valve spool 2 consists of magnetically well conducting soft iron. The member 2 is at the sliding areas, i.e. at the cylindrical surfaces of the valve spool webs 17 and 18, case-hardened. The valve spool section 9 has two spool webs 17 and 18 which at those end faces which face each other are provided each with a control edge 15, 16 cooperating with the control edges 5, 6 of the housing 1. The webs 17 and 18 are separated from each other by the plunger 19 which has a relatively large cross-section. The plunger 19 has a rather low magnetic resistance in view of its large cross-section and the material of which it is made. When the magnetic valve is in its de-energized condition, i.e. rest condition, a work air gap 20 is present between the movable magnetic core 3 and the pole cover 13. It is this gap 20 which has to be bridged when the magnetic core-valve spool 2 is attracted. A return spring 23 is provided on that side of the magnetic core-valve spool 2 which faces away from the magnetic core 3 and the coil 12. This spring 23 rests against the valve spool through the intervention of a spring ring 21.

The magnetic valve is provided especially for such liquids which can flow around the coil 12 without damaging the same. Therefore, no sea] is provided on the magnetic core between the bore for the valve spool and the coil chamber 1 1. The pole cover 13 is in a pressure-tight manner by means of an O-ring 25 and a four-cornered loose flange 26 screwed onto the end face of the housing 1 which has a four-cornered cross-section. One end of the wire wound up in the coil is extended to a cable terminal 14 which is electrically insulated and connected to the pole cover 13. The other end of said last mentioned wire is connected to the pole cover itself and is thus electrically connected to mass. The coil is centered over the fixed pole cover 13 in the housing 1. This cover collects or gathers the magnetic flux lines in the coil core so that the lines will at the working gap 20 all extend in axial direction.

When the coil is energized, a magnetic field is produced in the housing 1 the magnetic flux lines of which have their course determined primarily by the design of the housing. The said magnetic flux lines have a course which is diagrammatically shown in the drawing and designated with the letter I The said magnetic flux lines pass from the housing 1 through the fitting gap between the bore and the webs l7 and 18 into the valve spool and from there in part through the plunger 19 into the movable magnetic core 3. The magnetic flux which passes axially through the working gap 20 has the tendency to attract the magnetic core-valve spool 2 against the force of the spring 23 and thereby to close the gap. Inasmuch as this contacting surface of the valve spool at the interior of the valve spool bore is so large that the magnetic flux density does not exceed 1,000 Gauss, a jamming and/or seizing in view of the magnetic field in the fitting gap will thus practically be impossible. The magnetic core-valve spool 2 is in spite of passing the magnetic flux through the fitting gap completely freely movable without the danger of seizing.

It is, of course, to be understood that the present invention is, by no means, limited to the particular construction shown in the drawing but also comprises any modifications within the scope of the appended claims.

1. A magnetically actuated piston valve, which includes: a housing of magnetizable material comprising a valve cylinder means having a cylindrical bore, a piston valve spool having a cylindrical surface area, the piston valve spool being reciprocable in said bore and guided by said cylindrical surface area in said cylindrical bore, at least two openings connected with said bore for a liquid flow to be controlled by said valve cylinder means and said piston valve spool, magnetic coil means arranged within said housing and defining a central passage aligned with and adjacent to said cylindrical bore, armature means reciprocable in said passage, said housing forming a single and magnetically uniform piece, said piston valve spool and said armature means also forming a single unitary magnetically uniform piece, said cylindrical bore of said valve cylinder means and the cylindrical surface area of said piston valve spool forming the only paired surfaces for guidance of said piston valve spool and armature means and simultaneously forming the only paired surfaces for transfer of magnetic flux from said housing to said armature means.

2. A magnetically actuated piston valve according to claim 1, in which that surface area of said piston valve spool which contacts and is guided by said cylindrical bore is, during the operation of said valve, at least of such dimensions that during the energization of said coil means, the induction conveyed to said piston valve spool through the gap between said cylindrical bore and said piston valve spool does not exceed approximately 1,000 Gauss.

3. A magnetically actuated piston valve according to claim 1, in which said piston valve spool has two axially spaced cylindrical control sections and a plunger section interconnecting said cylindrical control sections.

4. A magnetically actuated piston valve according to claim 1, in which said piston valve spool consists of a magnetically well conductive steel.

5. A magnetically actuated piston valve according to claim 4, in which only a thin peripheral layer of said cylindrical control sections is hardened. 

1. A magnetically actuated piston valve, which includes: a housing of magnetizable material comprising a valve cylinder means having a cylindrical bore, a piston valve spool having a cylindrical surface area, the piston valve spool being reciprocable in said bore and guided by said cylindrical surface area in said cylindrical bore, at least two openings connected with said bore for a liquid flow to be controlled by said valve cylinder means and said piston valve spool, magnetic coil means arranged within said housing and defining a central passage aligned with and adjacent to said cylindrical bore, armature means reciprocable in said passage, said housing forming a single and magnetically uniform piece, said piston valve spool and said armature means also forming a single unitary magnetically uniform piece, said cylindrical bore of said valve cylinder means and the cylindrical surface area of said piston valve spool forming the only paired surfaces for guidance of said piston valve spool and armature means and simultaneously forming the only paired surfaces for transfer of magnetic flux from said housing to said armature means.
 2. A magnetically actuated piston valve according to claim 1, in which that surface area of said piston valve spool which contacts and is guided by said cylindrical bore is, during the operation of said valve, at least of such dimensions that during the energization of said coil means, the induction conveyed to said piston valve spool through the gap between said cylindrical bore and said piston valve spool does not exceed approximately 1,000 Gauss.
 3. A magnetically actuated piston valve according to claim 1, in which said piston valve spool has two axially spaced cylindrical control sections and a plunger section interconnecting said cylindrical control sections.
 4. A magnetically actuated piston valve according to claim 1, in which said piston valve spool consists of a magnetically well conductive steel.
 5. A magnetically actuated piston valve according to claim 4, in which only a thin peripheral layer of said cylindrical control sections is hardened. 